JPH0718235Y2 - Audio player - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] When switching the phase of a bass portion reproduced from a part of a plurality of speakers that output a reproduction sound of an audio signal, the level of the bass portion is changed almost continuously. A series of data is held in the holding unit in advance, and the data in this holding is sequentially input to the bass level setting unit by the phase switching means such as a switch, and the phase is switched while gradually changing the level of the bass. An audio playback device that performs
It is possible to prevent the reproduced sounds from the plurality of speakers from canceling each other out without generating an unnatural sound at the time of phase switching.

[Industrial application field]

The present invention relates to an audio reproducing device for reproducing an audio signal as a voice by a plurality of speakers.

For example, in a car or the like, when the plurality of speakers are arranged in front, rear, left and right of a listener in order to generate a desired sound field, the distance from each speaker varies depending on the position of the listener. There is. When the reproduced sounds output from the respective speakers are out of phase due to the difference in the distances and interfere with each other in the canceling direction, it becomes difficult for the listener to hear the reproduced sounds. Especially, in the low-pitched part with a long cycle, the time for mutual interference is long,
The above tendency becomes remarkable. The present invention refers to an audio reproducing apparatus having a function of preventing reproduced sounds from a plurality of speakers from being hard to hear due to interference between reproduced sounds.

[Conventional technology]

FIG. 6 is a block diagram showing a conventional audio reproducing apparatus. Generally, in the above audio reproducing apparatus, in addition to _a digital audio signal S _a directly obtained from a digital source 9 such as a compact disc (hereinafter abbreviated as CD) or a digital audio tape (hereinafter abbreviated as DAT), , A digital audio signal S obtained by A / D converting an analog audio signal from an analog source 9'such as a cassette tape by an A / D converter 19.
_a'is also entered.

In FIG. 6, the digital signals for appropriately processing the above audio signals S _a and S _a ′ to generate a desired sound field are shown.
A signal processing unit 4 having a signal processor (hereinafter abbreviated as DSP) and a CPU such as a microcomputer for controlling the operation of the DSP is provided. Furthermore, this signal processing unit 4
A plurality of D / A converters 6-1 to 6-4 for respectively D / A converting the plurality of digital reproduction signals from the analog reproduction signals S from the D / A converters 6-1 to 6-4. A plurality of amplifiers 7-1 to 7-4 for amplifying each _o to a predetermined level
And a plurality of speakers 8-1 to 8-which reproduce the amplified signals from the amplifiers 7-1 to 7-4 as voices, respectively.
And 4 are provided. However, here, in a certain space, for example, in the vehicle, the speakers 8-1, 8-2, 8-3 and 8-4 (hereinafter, the FL speaker 8-1, The case where the FR speaker 8-2, the RL speaker 8-3, and the RR speaker 8-4) are provided will be shown as a representative. In addition, audio signals can be
It is assumed that the bass parts of the reproduced sounds S _a and S _a ′ are emphasized and output from the RL speaker 8-3 and the RR speaker 8-4 arranged on the left and right rear parts.

If the distance between the RL speaker 8-3 and the listener is longer than the distance between the RR speaker 8-4 and the listener, the phase of the sound reproduced from the former speaker 8-3 is the latter speaker. Since the phase of the reproduced sound from 8-4 is delayed, both reproduced sounds interfere with each other. For example, when the phases of the two reproduced sounds are different from each other by 180 °, the reproduced sounds cancel each other almost completely, and the low-pitched sound is almost inaudible.

As a countermeasure against this, conventionally, a phase switching means 1 such as a switch is arranged on the front surface of a microcomputer or the like, and the phase switching means 1 is operated to change the filter coefficient or the like of the digital filter in the DSP in the signal processing section 4. As a result, the phase of the analog reproduction signal S _o corresponding to the speaker 8-4 of the RR is switched, for example, the signal level is inverted. By doing this, the phase of the reproduced sound from the speaker 8-4 of the RR becomes RL.
Since the phase is delayed to the same degree as the phase of the reproduced sound from the speaker 8-3 (for example, 180 °), there is no possibility that the reproduced sounds cancel each other.

[Problems to be solved by the device]

As described above, in order to prevent the reproduced sounds from the multiple speakers from canceling each other due to the phase shift and making the low-pitched part particularly difficult to hear, conventionally, the reproduced sound from a part of the multiple speakers has been reduced by a DSP or the like. The phase of was quickly switched so as to match the phase of the reproduced sound from other speakers.

However, in the high-speed signal processing unit 4 including the DSP and the like, as shown in FIG. 7, the signal waveform (in FIG. 7, the analog reproduction signal S _o ) usually changes discontinuously. Since the phase is switched instantaneously, an unnatural sound called pop noise is generated when the phase is switched. This clicking noise causes a problem that the listener feels uncomfortable.

The present invention has been made in view of the above problems, and the reproduced sounds from a plurality of speakers cancel each other without causing unnatural sound at the time of phase switching for correcting the reproduced sound, and the bass portion is reduced. It is an object of the present invention to provide an audio reproducing device capable of preventing the audio from becoming hard to hear.

[Means for Solving the Problems]

FIG. 1 is a block diagram showing the principle configuration of the present invention. However, hereinafter, only one audio signal S _a will be shown as a representative. Furthermore, a plurality of speakers 8 for outputting a reproduced sound of the audio signal S _a including at least a low tone part
An audio reproducing device in which -1 to 8-N are arranged will be shown. The same components as those described above are designated by the same reference numerals.

Here, a bass level setting unit 2 for setting the level of the bass portion reproduced from a part of the plurality of speakers 8-1 to 8-N is provided. Further, a holding unit 3 for holding a series of data for changing the level of the low-pitched portion almost continuously is provided.

More specifically, the bass level setting unit 2 changes the level of the bass portion almost continuously so that the level of the bass portion decreases and then rises again. In this case, the phase switching means 1 has a function of switching the phase of the low-pitched sound portion while the low-pitched sound level setting unit 2 lowers the level of the low-pitched sound portion.

[Action]

In FIG. 1, when it is desired to switch the phase of a part of the plurality of speakers 8-1 to 8-N, for example, the low-pitched part reproduced from the Nth speaker 8-N, the phase switching means 1 such as a switch is used. Then, a series of data in the holding unit 3 is sequentially called and input to the bass level setting unit 2. By doing so, the phase of the low-pitched sound portion is switched to a predetermined value while being gradually changed without being instantaneously inverted, so that unlike the conventional case, there is no possibility that a clicking sound is generated at the time of phase switching.

More specifically, in the present invention, in order to reduce discontinuity when switching between movements, the bass level is lowered, the phase is switched when this level is relatively low, and then the above-mentioned I try to restore the level. That is, by switching the phase when the signal level of the reproduced sound signal waveform is close to 0, the discontinuity of the signal waveform due to a large level fluctuation is prevented. For example, if the phase is switched when the signal level becomes 0, the discontinuity of the signal waveform does not occur in principle.

Thus, according to the present invention, it is possible to prevent the reproduced sounds from the plurality of speakers from canceling each other out and making the low-pitched sound difficult to hear without giving the listener an unpleasant sensation due to a clicking sound or the like.

〔Example〕

FIG. 2 is a circuit diagram showing an embodiment of the present invention. However, in this case, four speakers of FL, FR, RL and RR
1 illustrates an in-vehicle audio reproducing device in which 1,8-2,8-3 and 8-4 are arranged. Further, of the RL and RR speakers 8-3 and 8-4 which are output with the low-pitched part of the reproduced sound of the audio signal S _a emphasized, the RR speaker 8-
The case where the phase of the low-pitched part from 4 is switched is shown as a representative.

Here, the signal processing unit 4 and the bass level setting unit 2 (both of which are shown in FIG. 1) are connected to the audio signal S _a from a CD or DAT.
DSP5 that outputs a plurality of types (4 types in FIG. 2) of digital reproduction signals for performing a calculation process such as multiplication and addition to generate a desired sound field, and a microcomputer that controls the operation of the DSP5 It is realized with the CPU 10. In addition, the above DSP
Portion for outputting a digital reproduced signal corresponding to the speaker 8-4 RR at 5, a low-pass section 15 of the LPF or the like for passing only low-frequency audio signal S _a, in this low-pass unit 15 And a multiplier 25 connected thereto. In addition,
Details of the configuration of the other parts of the DSP 5 will be omitted. Further, as the phase switching means 1, a phase switching switch 11 is arranged on the front surface of the microcomputer. Further, as the holding unit 3, a ROM table 30 for storing a series of data in advance is attached to the CPU 10. Here, the series of data in the holding unit 30 is for adjusting the coefficient of the multiplier 25 in multiple stages to gradually change the level of the bass part reproduced from the speaker 8-4 of the RR. is there. In this case, 1
From 0.9 to 0.8, ... 0, −0.1, −0.2, ... −1, the data corresponding to the above coefficient is stored every 0.1. Furthermore, “0.
Labels PHSS1 and PHSE1 are added to the addresses where the 9 "data and" -1 "data are stored, respectively, and the" -0.9 "data and the" 1 "data are stored to the respective addresses. The labels PHSS2 and PHSE2 are added, and the means for performing the phase switching of the bass section by the CPU 10 of the microcomputer will be described in detail.

FIG. 3 is a flow chart for explaining the main operation of the CPU. When controlling the DSP5 by the CPU10,
First of all, all the registers and RAM in the microcomputer are reset to perform the initial settings. Next, the timer built in the microcomputer is operated to read the data input from various switches including the phase change switch 11 at regular intervals (steps a to d).

FIG. 4 is a flow chart for explaining the phase switching procedure. However, here, a case where the phase of the low sound portion reproduced from the speaker 8-4 of the RR is switched by 180 ° will be described as a representative. In this case, first, the phase changeover switch 11 is pressed to input data to the CPU 10. Next, in this CPU 10, it is determined whether the current phase is a positive phase or a negative phase, that is, whether the coefficient of the multiplier 25 is currently "1" or "-1". When the phase is positive, the normal phase flag is cleared (step f), and when the phase is negative, the normal phase flag is set (step h). Furthermore, when switching the phase from the positive phase to the negative phase, while incrementing the address PHSS1 to the address PHSE1 of the ROM table 30, the data in the address is sequentially called to keep the coefficient of the multiplier 25 in the DSP 5 constant. Set one after another at time intervals (step g). By doing this, the above coefficient becomes 0.1
It changes gradually with each change from "1" to "-1". As the coefficient changes, the signal level also gradually changes and finally
The phase switching of ° is completed. On the other hand, when switching from the negative phase to the positive phase, while decrementing the addresses PHSS2 to PHSE2 of the ROM table 30, the data in the above addresses are sequentially called and the above coefficients are set one after another (step i). In this way, the coefficient is gradually changed from "-1" to "1", and the phase switching is completed.

The phase switching operation described above, as is clear from FIG.
It is performed while changing the signal level almost continuously so as to be completed after a certain phase switching time has elapsed. Therefore, in the present embodiment (FIG. 2), the
Unlike the figure), no clicking noise is generated due to discontinuous changes in signal level. In addition, the microcomputer enables ROM
The length of the phase switching time can be suppressed to such an extent that there is no auditory problem simply by appropriately adjusting the time interval for level setting based on each data in the table 30.

[Advantages of the Invention] As described above, according to the present invention, the reproduced sounds from the plurality of speakers cancel each other without causing unnatural sound at the time of phase switching for the reproduced sound correction, and the bass part is canceled. An audio playback device that can prevent the inaudible noise from being heard is realized. Therefore, there is no possibility that the above-mentioned unnatural sound will make the listener feel uncomfortable.

[Brief description of drawings]

FIG. 1 is a block diagram showing the principle configuration of the present invention, FIG. 2 is a circuit diagram showing an embodiment of the present invention, FIG. 3 is a flow chart for explaining the main operation of the CPU, and FIG. 4 is phase switching. FIG. 5 is a flow chart for explaining the procedure, FIG. 5 is a diagram showing how the signal waveform changes during phase switching in the present embodiment, FIG. 6 is a block diagram showing a conventional audio reproducing apparatus, and FIG. It is a signal waveform diagram for demonstrating a problem. In the figure, 1 ... Phase switching means, 2 ... Bass level setting section, 3 ...
Holding unit, 4 ... Signal processing unit, 5 ... DSP, 8-1 to 8-
N ... Multiple speakers, 10 ... CPU.

Claims (1)

[Scope of utility model registration request] 1. A plurality of speakers (8-1 to 8-8) for outputting a reproduced sound of an audio signal (S _a ) including at least a bass part.
-N) and a phase switching means (1) for switching the phase of the bass part reproduced from a part of the plurality of speakers (8-1 to 8-N). A bass level setting section (2) is provided for changing the level of the bass section substantially continuously so that the level of the bass section rises and then rises again. The phase switching means (1) includes the bass level setting section (2). 2)
The audio reproducing apparatus is characterized in that the phase of the bass portion is switched while the level of the bass portion is lowered by.